March 16 Bryan Bergeron
My Sony integrated amp with copper chassis and huge toroidal transformers was a tour de force in my audio setup before the power mains took an indirect lightning hit. Because the microcontroller was fried, I couldn’t even get the unit to power up.
Without access to spare parts — including a new microcontroller assembly — I was at the mercy of factory certified technicians. And — because the unit was just out of warranty — I was going to be out $100 plus shipping in order to get an estimate on the repair.
Well, that amp is still sitting behind my workbench. Someday, I’ll find an identical amp on eBay, buy it for parts, and cobble together something that works. In the meantime, I decided to rebuild a McIntosh 240: a hot, bulky, but virtually indestructible tube amplifier. I spent a weekend replacing the electrolytic capacitors and swapping out the dozen vacuum tubes, one at a time.
The McIntosh 240 — like many other amps from the ‘60s and ‘70s — is unimpressive on paper. A mere 40 watts per channel, total harmonic distortion a whopping 0.5%, and a stripped down weight of 56 lbs. Plus, no remote.
Output is via massive potted output transformers through old-fashioned terminal strips. For less than the price of the vacuum tubes, I could have bought an NAD 3020D or similar solid-state stereo amplifier with superior specifications, the form factor of a paperback, and the all-important remote.
Although I’ll concede on the specifications front, I’ll counter that I prefer the warm coloration that vacuum tubes provide. Most of all, I know that I can repair the amp — regardless of what happens. The transformers are a bit scarce, but can be found on eBay and other online sources.
Otherwise, everything is ordinary electronics stock — capacitors, resistors, diodes, and vacuum tubes. Schematics and manuals are freely available on the Web, and there are numerous third parties that cater to vacuum tube amp owners.
Do I miss a remote? I can live without one. Am I concerned that vacuum tubes are about as far from “green” as an electric toaster? Not really, because I use the amp maybe 30 to 40 minutes a day.
Besides, I’m saving one more device from the landfills. And lightning strikes? Bring them on!
In this era of disposable unrepairable electronics, I suspect that there’s a growing demand for the simpler but workable electronics of the past.
If you’ve recently turned to vintage repairable electronics, I’d like to hear about it. NV
Posted on 03/16 at 4:21 pm
February 16 Bryan Bergeron
A friend in the marketing business contacted me about a project for a local retail store. He wanted to track customer satisfaction as customers exited the store by placing an Arduino-controlled survey taker. Customers would press one of five buttons as they left, indicating their experience from Very Satisfied to Not Satisfied. My friend envisioned five buttons connected to an Arduino, an LCD display, perhaps a beeper for button press feedback, and a battery pack capable of supporting the device for a week.
Seemed like a simple enough task. Too simple, in fact. After working up a straightforward program and defining the base hardware, we naturally progressed to planning a Wi-Fi interface so the counter could be accessed and reset remotely. That would require a simple web page, and maybe a couple hours of programming. We even evaluated a solar powered charger to obviate the need for a plug-in charger.
With plans in hand, we stood back, looked at the hardware and software involved, and the total cost. Then, we revisited the requirements. After a sanity check, we decided the complex Arduino-enabled survey device was overkill.
Starting over without a preconceived product, we identified a solution of five digital mechanical tally counters (or clickers) sold for coaches. We found suitable counters ranging from $2 to $5 each on Amazon. The counters — each the size of a walnut — easily fit on a plastic face plate with cutouts for each counter. And it worked. No batteries to worry about. No programming. And fully reusable counters once the survey was finished. Sure, there was no web interface and no way to check the tally at home on a smartphone, but there wasn’t a need.
The take-away from my experience was to avoid preconceived solutions to new problems. Sometimes expertise in one area unnecessarily narrows the range of options that should be considered when assessing a problem.
The caveat, of course, is that you shouldn’t pass up a chance to learn and expand your skill set. If your goal is to learn to work with an Arduino or other microcontroller and you have the time and funds, then go for it. Given the challenge above, why not have that Wi-Fi interface? Or, automatic cloud upload?
Go wild with the web interface, with visual and audible alarms, and graphics. Just don’t lose touch with what features and functions are really required. Experimenting is fantastic, but know when and how to apply your skills to practical problem solving. NV
Posted on 02/16 at 1:22 pm
January 16 Bryan Bergeron
I’ve been reading and writing about the imminent demise of leaded components for decades. Even so, at least half of my work still involves leaded components. After all, what’s not to like? Leaded components are easy to work with. It’s easy to identify the value of a leaded resistor or capacitor with the naked eye, and leaded components are readily available.
Besides, I’ve already committed the band values — red for two, orange for three, yellow for four, etc. — to long-term memory. Then, there’s the muscle memory of how to bend leads and how to work a soldering iron tip around the porcupine-like mass of leads when the component side is down.
Why let all that learning go to waste?
I don’t know what I would do without a good supply of 1/4 watt 10K leaded resistors to use as circuit probes. When I’m working with an Arduino or other microcontroller board, it takes only a few seconds to wire-wrap a 10K pull-up or pull-down resistor to an I/O pin. Try that with a surface-mount (or SMT) resistor.
Then, there’s the differential in infrastructure cost and workbench real estate. For leaded components, I have a simple Weller temperature controlled soldering iron, good old-fashioned needle-nose pliers, and desk lamp magnifier.
For surface-mount work, I have a hot air station that has the footprint of an oscilloscope, a tool drawer full of tweezers and stainless steel picks, and a half dozen containers of various solder pastes and fluxes.
And forget the magnified desk lamp — I have to don a Bosch & Lomb stereo magnifier and get my nose within inches of the board to see what’s going on.
One sneeze, of course, and every SMT component not glued or soldered down will be forever lost in the dust balls behind my workbench.
I know that experimenters aren’t alone in the battle between SMT and leaded components. I routinely tear down equipment for both fun and profit, and it’s unusual to find an electronic device devoid of leaded components.
Many of the inexpensive devices made in China — from drone controllers to electronic measuring devices — are made with a mystery chip embedded in a black epoxy blob that is surrounded with leaded capacitors and resistors.
This is understandable, given the cost of converting an electronics assembly plant from leaded to SMT devices. Unless you’re building iPhones or electronic watches, why upgrade an assembly plant unless you have to?
The bottom line is that if you’re just getting into electronics, don’t be dismayed — or distracted — by the world of SMT. A traditional perfboard, a good supply of leaded components, and a few schematics to work from will get you started.
When you’re ready to make your circuit semi-permanent, then break out your soldering iron or wire wrap tool. SMT components, the special boards, pastes, and the rest will be there if you ever need them. NV
Posted on 01/16 at 9:45 am
December 15 Bryan Bergeron
I’m often asked what the best way is to support STEM (Science, Technology, Engineering, and Math) education with electronics. At the high school level, as soon as I start talking about Arduino boards and sensors, teachers tend to run away. It’s intimidating to set up an electronics workshop from scratch. Think of all the necessary infrastructure that needs to be constructed — from multimeters and soldering irons to parts bins — and the components to fill them.
An alternative to a “made from scratch” approach is to use a kit or system that’s been preconfigured with sensors and the tools to collect and display the data in real time. I’ve used TechBasic ($15; ByteWorks.us) to turn my iPhone into a data collection platform.
I’ve gone as far as taping my phone to the spokes of my bike during an off-road excursion. The concern, of course, was losing my phone. As I’ve discussed in previous editorials, TechBasic enables you to access the various sensors in the iPhone, display the data graphically, and massage the data as you see fit — all using a variant of the BASIC language. I’ve seen videos in which users tie their cell phones to kites and even solid fuel model rockets.
A way to get your hands on data without putting your phone at risk is to use a wireless sensor such as the PocketLab ($98; thepocketlab.com). The 2.5” x 5/8” x 1-1/8” device is a BlueTooth-connected sensor cluster that collects data on temperature, barometric pressure, magnetic field, angular velocity position, and acceleration. The PocketLab is based on the TI CC2541, which I’ve used in the form of a fob-based evaluation kit available from Texas Instruments (TI). I found the hardware promising, but the software severely lacking. TechBasic provides support for the TI fob if you’re into programming.
The folks at PocketLab also addressed the software problem, adding in support for cloud storage/sharing — the real advantage of this device over TechBasic. Not only are data displayed in real time, but they automatically move from the PocketLab to your Android or iOS device to the cloud, where data can be downloaded to your laptop for evaluation, manipulation, and analysis.
Also, while the TI fob is a bit clunky, the PocketLab’s easy to handle plastic enclosure is mainly air, and the largest heaviest component by far is the coin battery. As an aside, PocketLab is one of those KickStarter success stories, raising $100K in the time they had hoped for $20K.
So, with environmental recorder in hand, what is one supposed to do to get all of this exposure to science, technology, engineering, and math? Well, as long as the experiment can be contained within the range of a Bluetooth device — say, in a classroom or on your person if you’re outside — it’s up to your imagination.
I wish I had access to a sensor-packed cell phone or an affordable wireless sensor package when I was studying Physics. I can still remember writing down rows of numbers from acceleration experiments. And forget about graphing results. That took hours.
So, in theory at least, with all the drudgery gone from doing science, everyone should be free to exercise their creativity, instead of spending time filling notebooks full of data. If you’ve used data collection and analysis as part of your STEM curriculum, please consider contributing to the reader forum so that other educators can learn from your experience. NV
Posted on 12/15 at 1:34 pm
December 15 Jeff Eckert
Let’s say you’re one of those folks who doesn’t like crowds and hate standing in line. As a result, you often decide to stay home to avoid the frustration of waiting for a table at your favorite restaurant, fighting the hoards for sale items at Macy’s, or bumping up against a herd of sweaty people at the gym. If so, you’ll be happy to hear about a new device from recent startup, Density (www.density.io).
The Density IR sensor is a basic people counter that — installed at the entrance to a public place — keeps track of how many people have entered and how many have exited, thus allowing it to provide both real time and historical data to help you decide when and if to drop in. Gathered information is collated by the Density Application Programming Interface and transmitted to a web application for use by a custom app.
For example, a company team is installing them in UC Berkeley gyms and other workspaces, and a Sacramento-based outfit called Requested (requestedapp.com) uses the system to generate restaurant discounts during off-peak periods. It doesn’t appear that a significant number of locations have Density installed at present, but who knows? It could catch on — especially given that hardware and installation are free. There is a monthly fee of $25, however, to use Density, but if it generates even a few extra customers, it seems well woth it. NV
Posted on 12/15 at 1:50 pm
December 15 Russ Shumaker
It was Christmas afternoon. The gifts had all been opened, and a substantial brunch had been consumed. The members of the household were all off doing their various things. The resident techie was wandering around the house with his new Dremel® tool, looking for something to grind, buff, drill, polish, or otherwise fold, spindle, or mutilate, when a voice called to him from somewhere in the house.
“Hon, have you checked the tree, lately?”
This was wife code talk for, “Add water to the Christmas tree, now please.”
Posted on 12/15 at 6:03 pm
November 15 Bryan Bergeron
When I started out in electronics, my “junk box” of rescued parts from TVs, radios, and the like was the source of endless projects and test instruments. Armed with a few key texts — especially the ARRL Handbook and Getting Started in Electronics by Forrest Mims — just about anything was possible.
Sure, my projects didn’t win any beauty contests with labels made with a permanent marker and reused chassis with dozens of extra holes, but most worked — eventually. It’s the “eventually” part that’s key.
I can recall dozens of blown circuit breakers, exploding electrolytic capacitors, and shorted vacuum tubes. However, I also recall the satisfaction of seeing copper, carbon, and steel come to life.
With time and savings, I later could buy just about anything that I wanted — from commercial test gear to top-of-the-line ham radio equipment. It made for a great looking test bench and ham shack, but I lost out on the learning end of things. It didn’t matter that I could read the schematic of the hermetically sealed phase locked loop synthesizer in my communications transceiver — I could never really know it. I could replace it if defective, but not really fix it the way I could one of my old creations.
From a practical perspective, having a nice portable o-scope with high bandwidth and Flash memory storage makes debugging a pleasure. Then, there’s the safety issue — none of my creations were UL listed or approved.
So, there’s nothing wrong with new gear that’s compact, safe, and easy to use. It’s just that — from an experimenter’s perspective — shiny commercial equipment can become a black box. I make a habit of disassembling everything I buy; in part to understand what’s in the black box, but it’s still an imperfect exercise.
If your goal is to maximize the learning experience — whether for yourself or someone you hope to pass on your knowledge of electronics to — then I’d consider the old school “junk box” approach to learning. Fill your box with parts from tear-downs of whatever you can get your hands on. It’s amazing what you can harvest from an old PC, for example. Even a discarded compact florescent bulb can yield a half dozen reusable components.
I’m fortunate to live a few miles from MIT, where there’s a regular flea market of used test gear and lab equipment that’s sold by the pound. Find out where your local ham or flea market is held and drop by at least once a year. Even if you don’t use parts harvested from the gear to build your own, the exercise of a tear-down is educational in itself.
You can’t wildly rip things apart, however. Take a methodical approach, trace the connections to see what components are associated with each other and — if you can — create a schematic diagram of the circuit in the device.
Lately, I’ve been partial to vacuum tube projects. With a few tubes and high voltage power supplies on hand, it doesn’t take much effort to build oscillators, tuners, sound effects devices, and so on. So, go ahead. Give the “old school” junk box method of setting up your workbench and your communications, robotics, or other projects a try. Your projects may not look as attractive as the commercial systems, but you’ll really understand the inner workings of what you build.
You’ll then be well on your way to being a real experimenter. NV
Posted on 11/15 at 8:57 pm
October 15 Bryan Bergeron
Magnetics, for the most part, make life easier. Consider what we’d do without the solenoids that actuate electric garage door motors, the rare-earth magnets embedded in iPad covers, magnetized tools, and the ubiquitous kitchen refrigerator magnets. However, the magnetic fields associated with magnets can be problematic.
For example, one of my interests is rebuilding vintage mechanical pocket watches. If you own a mechanical watch, you know that a magnetized watch will run abnormally fast. Well, I have a pocket watch on my desk that constantly gains time. I was at a loss to understand how the watch could become magnetized simply sitting on my desk. Well, using an inexpensive pocket compass, I was able to verify that the watch was being magnetized by a pair of scissors in a drawer directly under the watch. Opening and closing the drawer several times a day was enough to magnetize the watch — just as running a permanent magnet over a screwdriver can transform it into a magnet.
The discovery with my pocket watch led me to search for a magnetic free zone in my house. It was, in short, difficult. In my office, I have a dozen super magnets to hold papers on my white board. Then, there’s the unshielded speakers on the wall. In my kitchen, I was surprised to learn that some of the flatware was magnetized. On my dresser, I found my steel collar stays and magnet sets. It seemed my compass never really settled on magnetic North, given the various motors and electronic gadgets around my place.
In retaliation, I purchased a few degaussing machines from eBay, where they can be had for about $10 and up. First up was the fixed magnet combined magnetizer/demagnetizer. These devices work great as magnetizers for long thin objects such as screwdrivers, but are useless in reversing the process.
Next, I tried the generic Chinese-built “blue box” demagnetizer — essentially an AC solenoid without the moving parts and a momentary on switch. You place the screwdriver or other object you want to demagnetize on top of the box and press the button, which energizes the core with 110 VAC. Then, you slowly move the object away from the unit as far as you can before releasing the switch. The iron molecules within the tool or other object should be randomly aligned, and therefore non-magnetic. This solution was affordable, reliable, and consistent.
Given that I was looking for a solution on eBay, I also had a serendipitous find — an old US made “instantaneous demagnetizer” tool by Magna Flux ($20). This tool uses a capacitor discharge to quickly ramp down the magnetic field after it’s been built up. Like the blue boxes, it did the job. Moreover, there is no need to move the object to be demagnetized while the AC field is energized. Just press and release the button. The capacitor circuit takes care of decreasing the magnetic field.
Of course, if you decide to demagnetize your tools and mechanical watches, set up a safe area away from anything remotely resembling a magnetic data store. Don’t think of using a demagnetizer around your credit cards or your DAT collection.
With the magnetics out of the way, I’m left to puzzle over why a mechanical watch would run faster when magnetized. Is it somehow more efficient because of decreased friction? Are Eddy currents somehow imparting energy to the mainspring? Could magnetized motors somehow run more efficiently? If you have the answer, please drop me a line. NV
Posted on 10/15 at 9:08 am
Back in 2008, Nuts & Volts sponsored the $100 Workbench Challenge. It was a great success and we had plenty of readers enjoy participating in the contest and showing off their carefully crafted work spaces. With the changes in available tools and technology, we decided to bring the challenge back, but this time even bigger and with a lot more prizes! Our new two-part contest is a combination of straight-up workbench design and a bit of "show and tell." So, let’s get down to details. What exactly is the Workbench Challenge 2015? Check out the details...
Posted on 09/15 at 3:44 pm
September 15 Bryan Bergeron
With Amazon’s general release of the Echo home automation controller, it may be time to take a second look at the home automation market. I first took the plunge into commercial home automation several years ago with X10-compatible hardware (http://www.x10.com).
For the price of a bare-bones Echo ($180, www.Amazon.com), you can get a half dozen wireless timers and remotes for controlling lights, appliances, and your home security system. X10-compatible home automation devices are commodities — inexpensive, ubiquitous, and they work. Unfortunately, they’re also a bit boring.
At the other end of the home automation market are the cloudcompatible smart thermostats and cameras, typified by the Nest learning thermostat and Nest cam, respectively (www.nest.com). Both can be controlled through your smartphone from anywhere in the world. Plus, the learning thermostat is compatible with a variety of devices — from smart locks and sprinkler systems to ceiling fans.
If you want to make the Nest cam fully functional, you’ll have to pay a $10 monthly fee to Nest Aware — not something I’m prepared to do.
One of the advantages of the Amazon Echo is that it’s compatible with Belkin WeMo and Philips Hue devices. WeMo is compatible with standard Wi-Fi routers and iOS devices, such as the iPad. Hue — which is primarily for lighting — also works with a standard Wi-Fi router, and both iOS and Android tablets and smartphones.
I’ve used the Philips Hue lighting system with my iPhone for about a year. It’s expensive, however, at about $200 for a Wi-Fi/Hue bridge and three 60W equivalent LED bulbs. Which brings me to cost. The basic “star trek” package — which allows you to say the equivalent of “Computer, lights on” from anywhere in your living room — is about $400 — $180 for the Echo and $200 for a basic Philips Hue lighting system.
Add a few Belkin WeMo Wi-Fi switches for your existing lights or appliances, and you’re easily approaching $500. Still, this sort of off-the-shelf functionality that actually works was science fiction just a few years ago.
As Google, Apple, and now Amazon compete for the front end of the home automation market, there are likely to be more and more affordable peripherals and tools. More importantly — from an electronics enthusiast’s perspective — is the availability of inexpensive peripherals that can be easily torn down and repurposed for other uses. Think of replacing an RGB LED with three opto-isolators to control three servos, for example.
I think we just might have the “star trek” computer system of the 1960s. Now, someone needs to start working on the transporter, so we can say “Beam me up, Echo.” NV
Posted on 09/15 at 10:37 am